In the art, telecommunication equipment is often powered by high currents in −48V DC systems. The power consumption in such systems is subject to rapid variations due to fast fluctuations in radio output power. This leads to transients of the input currents which in turn causes voltage ripple that can damage batteries and disturb other devices in the system. Therefore, it is necessary to minimize, or at least reduce, the voltage ripple while at the same time being capable of handling the fluctuations in radio output power. For battery protection, relatively large-scale capacitors are used in connection to the battery.
The solution to this problem today is to use large reservoir capacitor banks as filters or energy storage to smooth the rippling current. These capacitors tend to be bulky, expensive and show poor reliability. There are, however, means to decrease the size of the capacitor banks.
One is to increase the voltage and thus the amount of energy stored in the capacitor bank. However, this solution is even more expensive, and provides poor power efficiency in the form of increased the power consumption. Moreover, reliability is poor and a further voltage increase may be dangerous. Another straightforward solution is to split up the capacitor bank and use resistors or inductors to form a low-pass filter, but drawbacks with this solution include additional power consumption of the resistors and size and cost of feasible inductors.